Allergic and non-allergic rhinitis are common disorders affecting about 30% of the population. Rhinitis has a considerable impact on quality of life. In fact, rhinitis is regarded to affect the quality of life more so than, e.g., asthma.
Hay fever and perennial allergic rhinitis are characterised by sneezing, rhinorrhea, nasal congestion, pruritus, conjunctivitis and pharyngitis. In perennial rhinitis, chronic nasal obstruction is often prominent and may extend to eustachian tube obstruction.
Oral or local antihistamines are first line treatments, and nasal steroids second line treatments for rhinitis. For most patients, topical corticosteroids and long acting antihistamine agents provide significant relief of symptoms. Antihistamines may also affect non-immunologically (non-IgE) mediated hypersensitivity reactions such as non-allergic rhinitis, exercise induced asthma, cold urticaria, and non-specific bronchial hyperreactivity.
Cetirizine dihydrochloride, [2-{4-[(4-chlorophenyl)-phenylmethyl]-1-piperazinyl}ethoxy]acetic acid is an orally and locally active, potent, long acting peripheral histamine H1 receptor antagonist. Cetirizine is one of the most widely used second generation antihistamines for the treatment of rhino-conjunctivitis and urticaria. It is effective, well tolerated and safe when used orally in a dose of 10 mg daily. Sedation and dry mouth do however occur as side effects in orally treated patients. Cetirizine is also approved in children for the treatment of rhinitis.
The main clinical affects of antihistamines include reduced sneezing and rhinorrhea. However, reduction of nasal blockage appears to be less responsive.
Local administration of antihistamines (such as azelastine and levocabastine) has advantages, including rapid onset of action and fewer side effects. At present, however, cetirizine dihydrochloride is not an approved medicine for local administration, although it has been administered in that manner in clinical trials.
In one trial (Francillon C, Pécoud A. Effect of nasal spray of cetirizine in a nasal provocation test with allergen. J Allergy Clin. Immunol. 1993:91, Suppl. 2:258 (abstract)), cetirizine nasal spray was found to reduce symptoms and increase nasal peak flow after an allergen challenge. Further, in exercise-induced asthma, a good protective effect was seen when cetirizine mist was administered to the lung with a nebulizer (Ghosh S K, De Vos C, McIlroy I, Patel K R. Effect of cetirizine on exercise induced asthma, Thorax 1991 April; 46 (4), 242-4).
Some effect was seen on symptoms when cetirizine (presumably as the dihydrochloride) was given as a nasal spray in patients with perennial allergic rhinitis. Concentrations of 0.625, 1.25, and 2.5 mg/mL of cetirizine were sprayed three times a day for two weeks (Clement P, Roovers M H, Francillon C, Dodion P. Dose-ranging, placebo-controlled study of cetirizine nasal spray in adults with perennial allergic rhinitis, Allergy 1994 September; 49 (8), 668-72). The most common side effects were related to nasal events, although no difference in incidence between the placebo and the cetirizine-treated groups was seen. However, the authors of this article speculated therein that local irritation had an adverse effect on treatment efficacy.
Indeed, due to the irritation of the nasal mucosa by cetirizine, it has been found to be necessary to decrease its immediate exposure in nasal administration. In European Patent No. EP 605 203 B1, it has been reported that this can be achieved by providing cetirizine in form of a composition containing cyclodextrin.
Liposomes (also known as lipid vesicles) are colloidal particles that are prepared from polar lipid molecules derived either from natural sources or chemical synthesis. Such spherical, closed structures composed of curved lipid bilayers, are typically used to entrap drugs, which are often cytotoxic, in order to reduce toxicity and/or increase efficacy. Liposome-entrapped drug preparations are often provided in a dry (e.g. freeze-dried) form, which is subsequently reconstituted with an aqueous solution immediately prior to administration. This is done in order to minimise the possibility of leakage of e.g. cytotoxic drug into aqueous solution and thereby reducing the entrapping effect of the liposome.
Liposomes have also been employed to encapsulate various drug compounds for delivery via the nasal route, in order to improve bioavailability or as an adjuvant. Drugs that may be mentioned include tetanus toxoid vaccine, insulin, desmopressin and diphenhydramine hydrochloride (see Türker et al, Review Article: Nasal Route and Drug Delivery Systems, Pharm, World Sci., 2004; 26, 137-142 and the references cited therein), as well as ciprofloxacin, CM3 and salbutamol (see Desai et al, A Facile Method of Delivery of Liposomes by Nebulization, J. Control. Release, 2002; 84, 69-78).
Liposome-entrapped cetirizine has also been administered topically to evaluate peripheral antihistaminic activity and systemic absorption in a rabbit model (Elzainy et al, Cetirizine from Topical Phosphatidylcholine-Hydrogenated Liposomes, The AAPS Journal, 2004; 6, 1-7. See also Drug Development and Industrial Pharmacy, 2005; 31, 281-291).
The lipophilic behaviour of the cationic (wherein the anion is chloride), zwitterionic, and anionic forms of cetirizine in buffered aqueous phosphatidylcholine liposome systems containing from about 1 to 33.5 mg/mL of phospholipid has also been studied (Plemper van Balen G at al., Lipophilicity behaviour of the zwitterionic antihistamine cetirizine in phosphatidylcholine liposomes/water systems, Pharm. Res. 2001; 18, 694-701). The aim with the study, in which separate solutions of PBS-diluted egg phosphatidylcholine liposomes were poured into separate compartments of dialysis cells, was to gain insight into the mechanism of interaction of the various electrical species of cetirizine and other drugs with liposomal membranes. The zwitterionic form of cetirizine, which dominates in the pH range of from about pH 4 to about pH 7, and even from about pH 3 to about pH 8, was considered by the authors of this article to be prevented from entry into the liposomal membrane by rendering the formation of lipophilic folded conformers of cetirizine more difficult. In this respect, cetirizine was not entrapped in liposomal membranes for delivery of drug to patients.
To the applicant's knowledge there is no prior disclosure or suggestion in the art of a homogeneous pharmaceutical composition comprising zwitterionic cetirizine, a polar lipid liposome and a pharmaceutical acceptable aqueous carrier.
Surprisingly, we have found that the irritation normally associated with (e.g. nasal) administration of cetirizine may be reduced by way of use of just such a composition.
According to the invention, there is provided pharmaceutical compositions suitable for the treatment of rhinitis by, for example, nasal or ocular administration comprising zwitterionic cetirizine, a polar lipid liposome and a pharmaceutical-acceptable aqueous carrier, which compositions are referred to hereinafter as “the compositions of the invention”.
The skilled person will appreciate that zwitterionic cetirizine is employed in compositions of the invention in a pharmacologically-effective amount (vide infra). The term “pharmacologically-effective amount” refers to an amount of cetirizine, which is capable of conferring the desired therapeutic effect on a treated patient, whether administered alone or in combination with another active ingredient. Such an effect may be objective (i.e. measurable by some test or marker) or subjective (i.e. the subject gives an indication of, or feels, an effect).
By “pharmaceutical compositions” we include compositions that are suitable for use in direct administration to mammals, and especially humans. In this respect, the term is intended to encompass formulations that include only components that are regarded in the art as suitable for administration to mammalian, and especially human, patients. In the context of the present invention, the term may also mean that the compositions of the invention are in a form of a liquid that is ready-to-use, directly from the shelf, and not a formulation in which drug is encapsulated inside liposomes requiring reconstitution shortly prior to administration in order to avoid leakage of drug from liposomes into an aqueous carrier.
The compositions of the invention are preferably homogeneous. By “homogenous” we include not only that the compositions of the invention comprise liposomes dispersed evenly throughout the aqueous carrier, but further that the active ingredient is distributed throughout the whole composition in a substantially similar concentration in the relevant aqueous medium, whether that medium is located inside or outside of the liposomal structures. By “substantially similar”, we include that the concentration may vary by about ±50%, such as about ±40%, preferably about ±30%, more preferably about ±20% and particularly about ±10% (when comparing concentrations inside and outside of the liposomal structures) at room temperature and atmospheric pressure. Drug concentration profiles may be measured by standard techniques known to the skilled person, such as 31P-NMR. For example, a standard in situ probing technique, or a technique that involves separation of the liposomal fraction from the free aqueous carrier and measurement of the amount/concentration of drug associated with each fraction may be employed. Separation may be accomplished by centrifugation, dialysis, ultrafiltration, or gel filtration.
It is preferred that the compositions of the invention further include a pharmaceutically-acceptable buffer capable of providing a pH of from about pH 4 (e.g. 4.0) to about pH 8 (e.g. 8.0), preferably from about pH 5 (e.g. 5.0) to about pH 7 (e.g. 7.0). Appropriate buffers include those that will not interfere with the formation of liposomes, such as a phosphate (e.g. disodium phosphate, dipotassium phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate or phosphoric acid plus base), citrate (e.g. sodium citrate or citric acid plus base), or acetate buffer (e.g. sodium acetate or acetic acid plus base), which is capable of maintaining a pH within the above-specified ranges. Buffers may be employed in an amount that is suitable to provide for the above-mentioned effects and such will be appreciated by the skilled person without recourse to inventive input. Appropriate quantities are for example in the range of about 1 mg/mL to about 30 mg/mL.
Any pharmaceutically-acceptable salt of cetirizine as well as the free base form thereof may be used in the manufacture of compositions of the invention. Preferred salts include chloride salts, hydrochloride (e.g. dihydrochloride) salts and, more particularly, nitrate salts of cetirizine, most preferably cetirizine dinitrate.
The amount of cetirizine or salt thereof that may be employed in preparation of compositions of the invention may be determined by the physician, or the skilled person, in relation to what will be most suitable for an individual patient. This is likely to vary with the severity of the condition that is to be treated, as well as the species, age, weight, sex, renal function, hepatic function and response of the particular patient to be treated. It is preferred however that the compositions of the invention comprise cetirizine or a salt thereof in an amount of from about 1 mg/mL to about 30 (e.g. about 25, such as about 23) mg/mL calculated on the zwitterionic form, preferably in an amount of from about 5.5 mg/mL to about 22 mg/mL. A further preferred range is between about 6 mg/mL and about 15 mg/mL, such as about 8 mg/mL to about 12 mg/mL.
In such a case, the total amount of active ingredient that may be present may be sufficient to provide a daily dose of drug per unit dosage that is in the range about 4 mg to about 20 mg, such as about 5 mg to about 15 mg, more preferably about 7 mg to about 12 mg and most preferably about 8 mg to about 10 mg. The skilled person will appreciate that compositions of the invention may be dosed once or more times daily in one or more administrations in order to provide the aforementioned daily dose.
The above-mentioned dosages are exemplary of the average case; there can, of course, be individual instances where higher or lower dosage ranges are merited, and such are within the scope of this invention.
The term “liposome” will be well understood by those skilled in the art to include a structure consisting of one or more concentric spheres of polar lipid bilayers separated by water or aqueous buffer compartments.
Liposomes may be prepared by various methods using solvents, reduced pressure, two-phase systems, freeze drying, sonication etc. described, for instance, in Liposome Drug Delivery Systems, Betageri G V et al., Technomic Publishing AG, Basel, Switzerland, 1993, the relevant disclosures in which document are hereby incorporated by reference.
The term “polar lipid” will be well understood by the skilled person to include any lipid with a polar head-group and two fatty acid residues, which is capable of forming liposomes.
Polar lipids, such as those described hereinafter, may be of a natural and/or a synthetic/semi-synthetic origin. Mixtures of natural and synthetic/semi-synthetic polar lipids may also be employed in compositions of the invention.
Polar lipids that may be employed in compositions of the invention may thus be based on, for example, phospholipids, and in particular phosphatidylcholine (PC), phosphatidylglycerol (PG), phosphatidylinositol (PI), phosphatidic acid (PA), phosphatidylserine (PS), or mixtures thereof.
Phospholipids that may be employed in compositions of the invention comprise polar and non-polar groups linked to a backbone entity carrying hydroxyl groups, such as glycerol.
Phospholipids may also be represented by the general formula I
wherein R1 and R2 independently represent a saturated or unsaturated (e.g. alkenyl), branched or straight chain alkyl group having between 7 and 23 carbon atoms, preferably between 11 and 19 carbon atoms; and R3 represents an amide or ester bonding group, such as    —CH2—CH(OH)—CH2OH (phosphatidylglycerol),    —CH2—CH2—N(CH3)3 (phosphatidylcholine),    —CH2—CH2—NH2 (phosphatidylethanolamine),    —H (phosphatidic acid), or    —CH2—CH(NH2)—COOH (phosphatidylserine).
The phospholipid may be of natural origin. Natural phospholipids are preferably membrane lipids derived from various sources of both vegetable (e.g. rapeseed, sunflower, etc., or, preferably, soybean) and animal origin (e.g. egg yolk, bovine milk, etc.). Phospholipids from soybean, a major source of vegetable phospholipids, are normally obtained from the by-products (i.e. lecithins) in the refining of crude soybean oil by the degumming process. The lecithins are further processed and purified using other physical unit operations, such as fractionation and/or chromatography. Other phospholipids may be obtained, for example, by pressing various suitable seeds and grains, followed by solvent extraction and then further processing as described above, Phospholipids of natural origin that may be mentioned include for example those that are available under the tradenames Lipoid S75, Lipoid S100 and Lipoid S75-3N (Lipoid GmbH, Germany), which are all blends of several different phospholipids that are found in soybean.
The phospholipid may alternatively be of synthetic or semi-synthetic origin (i.e. prepared by chemical synthesis). For example, a multi-step chemical synthetic approach may be used in order to obtain the key phospholipid intermediates, 1,2-diacylglycerol, from (S)-1,2-isopropylideneglycerol, the latter providing the glycerol backbone that is characteristic of phospholipids. 1,2-Diacetylated phospholipids may then be obtained when the corresponding polar head group is attached via chemical synthesis to the 1,2-diacylglycerol intermediate. Generally, however, the origin of glycerol and the fatty acids used in the various steps may be of both natural and synthetic origin. Synthetic and/or semi-synthetic phospholipids that may be mentioned include dilaurylphosphatidylcholine (DLPC), dimyristolphosphatidylcholine (DMPC), dipalmitoylphosphatidylcholine (DPPC), dilaurylphosphatidylglycerol (DLPG), dimyristolphosphatidylglycerol (DMPG), dioleoylphosphatidylcholine (DOPC) and dioleoylphosphatidylglycerol (DOPG).
The polar lipid may alternatively comprise or, more preferably, consist of a glycolipid. In the context of the present invention, the term “glycolipid” designates a compound containing one or more monosaccharide residues bound by a glycosidic linkage to a hydrophobic moiety such as an acylglycerol, a sphingoid or a ceramide (N-acylsphingoid).
A glycolipid may be a glycoglycerolipid. In the context of the present invention, the term “glycoglycerolipid” designates a glycolipid containing one or more glycerol residues. According to a preferred aspect of the invention, the glycoglycerolipid comprises, or consists of, galactoglycerolipid, more preferably a digalactosyldiacylglycerol of the general formula II,
wherein R1 and R2 are as hereinbefore defined.
The glycolipid may alternatively be a glycosphingolipid. In the context of the present invention, the term “glycosphingolipid” designates a lipid containing at least one monosaccharide residue and either a sphingoid or a ceramide. The term may thus comprise neutral glycophingolipids, such as mono- and oligoglycosylsphingoids as well as oligo- and, more preferably, monoglycosylceramides. The teen additionally comprises acidic glycosphingolipids such as sialoglycosphingolipids, uronoglycosphingolipids, sulfoglycosphingolipids, phosphoglycosphingolipids, and phosphonoglycosphingolipids. The glycosphingolipid can be ceramide, monohexosylceramide, dihexosylceramide, sphingomyelin, lysosphingomyelin, sphingosine, or a mixture thereof. Preferably the glycosphingolipid is sphingomyelin or products derived therefrom. The sphingomyelin content is preferably established by chromatographic methods, Sphingomyelin may be extracted from milk, preferably bovine milk, brain, egg yolk or erythrocytes from animal blood, preferably sheep. For the avoidance of doubt, synthetic and semi-synthetic sphingolipids are comprised by the invention.
The glycolipid may alternatively be a glycophosphatidylinositol. In the context of the present invention, the term “glycophosphatidylinositol” designates a glycolipid containing saccharides glycosidically linked to the inositol moiety of phosphatidylinositols.
Preferred glycolipids include digalactosyldiacylglycerol (DGDG).
Preferred polar lipids (such as phospholipids) are those that swell to a measurable degree in water and/or those which are capable of spontaneous liposome formation.
If the polar (e.g. phospho-) lipid does not swell spontaneously in water, the skilled person will appreciate that it is nevertheless possible to obtain liposomes by adding a more polar, swellable (e.g. phospho-) lipid, such as an anionic (e.g. phospho-) lipid (e.g. phosphatidylglycerol).
Liposome formation may be performed at above about 0° C. (e.g. room temperature) if the phase transition temperature of the acyl chains (chain melting; gel-to-liquid crystals) is below the freezing point of water.
Whichever polar lipid substance (or combination thereof) is used, suitable total amounts/concentrations of lipid(s) that may be employed in preparation of a composition of the invention are in the range of about 10 mg/mL to about 120 mg/mL. Compositions of the invention that may be mentioned include those in which, when the polar lipid comprises phospholipid (whether in combination with another lipid or otherwise), the amount of phospholipid(s) in the composition is from about 10 (e.g. about 17, such as about 20) mg/mL to about 120 mg/mL, more preferably from about 25 (e.g. about 35) mg to about 100 (e.g., about 70, such about 50, e.g. about 40) mg/mL.
Compositions of the invention may also comprise an antioxidant, such as α-tocopherol, ascorbic acid, butylated hydroxyanisole, butylated hydroxytoluene, citric acid, fumaric acid, malic acid, monothioglycerol, propionic acid, propyl gallate, sodium ascorbate, sodium bisulfite, sodium metabisulfite, potassium metabisulfite, sodium sulfite, tartaric acid or vitamin E.
According to the invention a chelating agent may be used to reduce the metal ion catalysed oxidation of phospholipid and/or cetirizine. Examples of useful chelating agents are ethylenediaminetetraacetic acid (EDTA), ethylenediaminetriacetic acid and diethylenetriaminepentaacetic acid (DTPA). It is also possible to use other agents that protect the composition of the invention and, in particular, any unsaturated fatty acid residues that may be present therein, from oxidation.
The composition of the invention can comprise one or more preservatives. Examples of common preservatives for liquid pharmaceutical compositions are benzalkonium chloride, benzoic acid, butylated hydroxyanisole, butylparaben, chlorbutanol, ethylparaben, methylparaben, propylparaben, phenoxyethanol or phenylethyl alcohol.
In order to retain the composition of the invention at its application site it may also comprise viscosity-increasing agent such as, for instance, hydrophilic polymers like polyethyleneglycol, or crosslinked polyvinylpyrrolidone and/or cellulose derivatives such as hydroxypropylmethyl cellulose. Viscosity increasing agents may also function as protective colloids to physically stabilise the composition of the invention prior to administration.
Compositions of the invention may also comprise flavourings (e.g. lemon, menthol or peppermint powder) and/or sweeteners (e.g. neohesperidin).
Compositions of the invention may also comprise tonicity-modifying agents, such as sodium chloride; potassium chloride, glycerol, glucose, dextrose, sucrose, mannitol, etc.
Optional additives, including buffering agents, preservatives, viscosity-increasing agents, antioxidants, tonicity-modifying agents and chelating agents should be selected, in terms of their identity and the amounts employed, keeping in mind that their detrimental effect on liposome stability should be kept at a minimum. For a given agent this can be ascertained by simple experiments, which are well within the understanding of the skilled person. Suitable amounts of such ingredients are however in the range about 0.01 mg/mL to about 10 mg/mL.
There is also provided a process for preparing compositions of the invention. We have surprisingly found that liposomes may be prepared by direct swelling of the polar lipids in an aqueous medium without the addition of any other excipients such as charged lipids and/or surfactants etc., which are normally required.
According to a further aspect of the invention, there is provided a process for preparing a composition of the invention, which process comprises:
(a) providing a polar lipid or a mixture of polar lipids that is/are swellable in aqueous media;
(b) providing an aqueous solution of cetirizine;
(c) adding the polar lipid or mixture to the aqueous solution with stirring, thereby forming a cetirizine liposome preparation;
(d) optionally adjusting the pH of the preparation to a desired value within the range of from about pH 4 (e.g. 4.0) to about pH 8 (e.g. 8.0), preferably from about pH 5 (e.g. 5.0) to about pH 7 (e.g. 7.0), by adding an acid or a base (e.g. hydrochloric acid and/or sodium hydroxide at an appropriate concentration (e.g. 1M));(e) optionally adding buffer solution or, more preferably, water or saline to the preparation to obtain a desired final batch volume; and(f) homogenising the preparation to obtain said pharmaceutical composition.
Solutions/liquids may be purged with nitrogen or argon at a suitable stage in the above process, if and as appropriate.
In the context of the present invention, a lipid may be said to be swellable in aqueous media if, when placed in contact with such a medium, it swells to a measurable degree.
Buffers may preferably be added to the aqueous solution of drug (and/or drug may be added to an aqueous buffer solution) prior to the addition of lipid. This notwithstanding, the person skilled in the art will be aware of the inherent buffering effect of zwitterionic cetirizine.
The formation of the liposomes of the invention may be facilitated by the spontaneous swelling of the polar lipid in water forming a lamellar liquid crystalline phase having a maximum water content of about 35% by weight or higher depending on the nature of the polar lipid, Depending on the lipid or lipid mixture used and other conditions, spontaneous formation of liposomes may be achieved when excess water is added to this lamellar phase. If spontaneous formation is not achieved, the formation of liposomes may be accomplished by the mechanical dispersion step (i.e. the homogenisation step (f) of the above process) of the lamellar liquid-crystalline phase in excess water.
Homogenisation/dispersion methods include vigorous mechanical mixing, for instance by means of an Ultra Turrax® (Jankel & Kühnke, Germany), Shaking, vortexing and rolling may also be performed as part of the homogenisation step of the above process.
A homogeneous size distribution of the liposomes of the invention may be desirable and may be obtained by extrusion through a membrane filter, such as one made of polycarbonate, with a pore size of about 100 nm. Membrane filters may be procured from Avestin Inc., Canada.
A reduced average liposome size and narrowed liposome size distribution may preferably also be obtained when the liposomal dispersion is subjected to high-pressure homogenisation with a suitable homogeniser (Rannie APV, type 7.30 VH, Rannie AS, Denmark) at, for example, between about 300 bar and about 1000 bar, such as between about 400 bar and about 900 bar, e.g. about 500 to about 800 bar for between about 4 and about 8 (e.g. 7, such as 6) cycles.
Surprisingly, we have found that the presence of cetirizine results in a reduction of liposome size. Smaller liposomes are generally advantageous because they are more stable physically and, due to their higher surface area/volume ratio, are more easily resorbed by the mucosa.
We prefer that the diameter of liposomes in compositions of the invention is less than about 200 nm (e.g. between about 40 to about 100 nm), as measured by, for example, laser diffraction or dynamic light scattering, e.g. as described hereinafter.
Furthermore, the above-mentioned process for the preparation of compositions of the invention does not normally require conventional treatment with organic solvents such as chloroform or dichloromethane. However, if two or more membrane lipids are used it may be appropriate and/or necessary to treat them with organic solvent prior to the addition of the aqueous solvent. For example, the lipids may be dissolved in a volatile solvent or solvent mixture, such as chloroform or chloroform/methanol. The solution may then be deposited on the surfaces of a round-bottomed flask as the solvent is removed by rotary evaporation under reduced pressure. An excess volume of aqueous buffer containing the drug may then be added to the dry thin film of lipids, which may then be allowed to swell to form liposomes.
The compositions of the invention are useful in the treatment of any indication for which cetirizine is known to be indicated, including rhinitis. The term “rhinitis” will be understood to include any irritation and/or inflammation of the nose, whether allergic or non-allergic, including seasonal rhinitis (e.g. caused by outdoor agents such as pollen; hay fever) and/or perennial rhinitis (e.g. caused by house dust mites, indoor mold etc), as well as the symptoms thereof.
According to a further aspect of the invention, there is provided a method for the treatment of rhinitis comprising the (e.g. nasal) administration of a pharmacologically-effective amount of a composition of the invention to a person suffering from or susceptible to that disorder.
For the avoidance of doubt, by “treatment” we include the therapeutic treatment, as well as the symptomatic treatment, the prophylaxis, or the diagnosis, of a condition.
The compositions of the invention may be administered by way of a nasal spray, nasal drops and/or eye drops. It is also possible to administer compositions of the invention as a fine mist to the lungs by nebulization. For nasal administration, any state-of-the-art device suitable for producing sprays of aqueous liposomal dispersions may be used.
Wherever the word “about” is employed herein in the context of dimensions (e.g. pH values, sizes, temperatures, pressures, etc.) and amounts (e.g. amounts, weights and/or concentrations of individual constituents in a composition or a component of a composition, proportions of drug inside/outside the liposomal structures, absolute doses of active ingredient, etc.), it will be appreciated that such variables are approximate and as such may vary by ±10%, for example ±5% and preferably ±2% (e.g. ±1%) from the numbers specified herein.
The compositions of the invention, and the above-mentioned process that may be employed for their preparation, have the advantages that are mentioned hereinbefore. In particular, compositions of the invention may reduce the incidence of inconvenient side-effects (and in particular irritation) that are normally observed with e.g. nasally-administered cetirizine formulations.
Compositions of the invention are easy to manufacture and enable the production of liposomal-based formulations that are in a ready-to-use form, avoiding the need for reconstitution prior to administration.
Compositions of the invention may also have the advantage that they may be prepared using established pharmaceutical processing methods and employ materials that are approved for use in foods or pharmaceuticals or of like regulatory status.
Compositions of the invention may also have the advantage that they may be more efficacious than, be less toxic than, be longer acting than, be more potent than, produce fewer side effects than, be more easily absorbed than, and/or have a better pharmacokinetic profile than, and/or have other useful pharmacological, physical, or chemical properties over, pharmaceutical compositions known in the prior art, whether for use in the treatment of rhinitis or otherwise.
The invention is illustrated by way of the following examples.